<!doctype html> 
<html> 
<head> 
    <meta charset="utf-8"> 
    <title></title> 
</head>
<body>
<div id='sad' lll='asd'></div>
<script type="text/javascript">
//var a = false;
//alert(document.body.id)
//alert('lll' in sad)
//alert(window.a)
/*
if(a){
	alert('有')
}
else{
	alert('没有')
}
*/

</script>
</body>
</html>